Braking of motor vehicles sets up considerable stresses in the brake components which accordingly deflect, to a greater or lesser extent depending on the loading on and nature of the particular component. Disc brake assemblies are no different and FIG. 1 of the attached drawings depicts diagrammatically a prior art disc brake assembly under braking conditions. As shown in FIG. 1 a disc brake assembly 1 includes a caliper 2 on the inboard side of which a cylinder 3 is integrally formed. A piston (not shown) is slidable within the cylinder 3 and is connected to an inboard pad assembly 4. An outboard pad assembly 5 is connected to the outboard side of the caliper 2 and the two pad assemblies are arranged to clamp onto a disc 6 which is mounted to rotate with the motor vehicle on which the assembly is mounted. An anchor bracket 7 is fixed to the vehicle and slideways 8 are formed on the anchor bracket. The slideways 8 serve to support and guide the pad assemblies 4 and 5 under braking conditions. As shown in an exaggerated manner in FIG. 1 there is a tendency for the anchor bracket 7 to deflect under load which in turn results in the caliper tilting relative to the axis of rotation of the disc and hence uneven loading being applied by the pad assemblies. The friction pads 9 of the pad assemblies tend to taper after continued use and this leads to brakes off, brake drag and reduced performance due to skew pad pressure distribution. Reduced pad life also results.
This problem applies to the caliper of both pad guided or pin guided constructions. This problem can be reduced to some extent by making the anchor bracket less deflectable by, for example, providing a tie bar (indicated by dotted lines 10) on the outboard side of the bracket, or alternatively making the anchor bracket stronger. Both these solutions result in an anchor bracket which is substantially heavier than is desirable, and is accordingly more expensive The weight factor is imPortant since there is a need to keep vehicle weight as low as possible to thereby enhance vehicle operational characteristics. It has also been found that, although the deflection is reduced using either of these solutions, deflection does still occur which is undesirable.
A further disadvantage of prior art disc brake assemblies is complexity of manufacture, limited possibilities to utilize assemblies in a variety of vehicles, high cost of manufacture, and high weight.
A further problem arises as a result of vehicle variations. It will be appreciated that motor vehicles require a brake system which is specifically adapted to compliment the characteristics of that vehicle, and accordingly, where disc brakes are used, disc diameters and brake components are selected to compliment each particular model of vehicle. Motor vehicle manufacturers now produce wide ranges of models having differing weights and speeds and accordingly, it has been necessary to produce a wide range of disc brake assemblies. The necessity to provide this range adds significantly to the cost of assemblies, particularly where a particular assembly is only required for a short production run, as the capital outlay needed to produce a particular assembly has to be recouped from only a limited number of items.
It is an object of the invention to provide a disc brake assembly in which the abovementioned pad taper problem is diminished to a significant extent. A further object is to provide a caliper which allows for a light weight disc brake assembly. A yet further object of the invention is to provide a disc brake assembly suitable for use on a variety of vehicles which requires only minimum adaptation for different vehicles.